Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

Fe-binding and storage protein; During stationary phase, binds the chromosome non- specifically, forming a highly ordered and stable dps-DNA co-crystal within which chromosomal DNA is condensed and protected from diverse damages. It protects DNA from oxidative damage by sequestering intracellular Fe(2+) ion and storing it in the form of Fe(3+) oxyhydroxide mineral, which can be released after reduction. One hydrogen peroxide oxidizes two Fe(2+) ions, which prevents hydroxyl radical production by the Fenton reaction. Dps also protects the cell from UV and gamma irradiation, iron and cop [...]

leucyl/phenylalanyl-tRNA-protein transferase; Functions in the N-end rule pathway of protein degradation where it conjugates Leu, Phe and, less efficiently, Met from aminoacyl- tRNAs to the N-termini of proteins containing an N-terminal arginine or lysine; Belongs to the L/F-transferase family.

ATPase and specificity subunit of ClpX-ClpP ATP-dependent serine protease; ATP-dependent specificity component of the Clp protease. Uses cycles of ATP binding and hydrolysis to unfold proteins and translocate them to the ClpP protease. It directs the protease to specific substrates both with and without the help of adapter proteins such as SspB. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. It may bind to the lambda O substrate protein and present it to the ClpP protease in a form that can be recognized a [...]

Putrescine:2-oxoglutaric acid aminotransferase, PLP-dependent; Catalyzes the aminotransferase reaction from putrescine to 2- oxoglutarate, leading to glutamate and 4-aminobutanal, which spontaneously cyclizes to form 1-pyrroline. This is the first step in one of two pathways for putrescine degradation, where putrescine is converted into 4- aminobutanoate (gamma-aminobutyrate or GABA) via 4-aminobutanal, which allows E.coli to grow on putrescine as the sole nitrogen source. Also functions as a cadaverine transaminase in a a L-lysine degradation pathway to succinate that proceeds via cad [...]

ClpXP protease specificity enhancing factor; Enhances recognition of ssrA-tagged proteins by the ClpX-ClpP protease; the ssrA degradation tag (AANDENYALAA) is added trans- translationally to proteins that are stalled on the ribosome, freeing the ribosome and targeting stalled peptides for degradation. SspB activates the ATPase activity of ClpX. Seems to act in concert with SspA in the regulation of several proteins during exponential and stationary-phase growth.

Protein disaggregation chaperone; Part of a stress-induced multi-chaperone system, it is involved in the recovery of the cell from heat-induced damage, in cooperation with DnaK, DnaJ and GrpE. Acts before DnaK, in the processing of protein aggregates. Protein binding stimulates the ATPase activity; ATP hydrolysis unfolds the denatured protein aggregates, which probably helps expose new hydrophobic binding sites on the surface of ClpB-bound aggregates, contributing to the solubilization and refolding of denatured protein aggregates by DnaK.

Chaperone Hsp70, with co-chaperone DnaJ; Plays an essential role in the initiation of phage lambda DNA replication, where it acts in an ATP-dependent fashion with the DnaJ protein to release lambda O and P proteins from the preprimosomal complex. DnaK is also involved in chromosomal DNA replication, possibly through an analogous interaction with the DnaA protein. Also participates actively in the response to hyperosmotic shock.

PcnB-degradosome interaction factor; Regulates the turnover of the sigma S factor (RpoS) by promoting its proteolysis in exponentially growing cells. Acts by binding and delivering RpoS to the ClpXP protease. RssB is not co- degraded with RpoS, but is released from the complex and can initiate a new cycle of RpoS recognition and degradation. In stationary phase, could also act as an anti-sigma factor and reduce the ability of RpoS to activate gene expression. Is also involved in the regulation of the mRNA polyadenylation pathway during stationary phase, probably by maintaining the asso [...]